A fleet of ships is on a straight course at a speed of one knot. It is guarded by a cruiser that travels at two knots.

A. The fleet is travelling in a single file one nautical mile long. The cruiser starts at the back and continuously motors to the front and to the back again. How long does one cycle take?

B. The fleet is in a square formation, one nautical mile on a side, two sides parallel to the direction of motion. The cruiser hems close to the side of this square as it travels up one side, across the front, down the other side, and across the back. How long does one cycle take?